But I tell my students to call me one of three things: Professor Hannah, Dr. Hannah, or Hiram. (Most students at my MidSouth regional uni call profs, Professor Whatever.) I actually write all three options on the board.
What do you think my freshmen call me.
I look at them the first time and I say, "I'd rather you call me Skeets, my childhood nickname, than MISTER Hannah."
They laugh. They leave the room at the end of class, "See you Thursday, Mr. Hannah."
One day I'm bringing a baseball bat to class with "Mr. Hannah" written on it with magic marker. I will say to them, "I'm the one who knocks." (BB ref.)